The present invention relates generally to facilitating and/or improving use of a digitizer cursor and, more particularly, to improving the accuracy of positioning a digitizer cursor. More particularly, the invention relates to a movably-mounted optical accessory used by the operator to more accurately make position determinations of the digitizer cursor.
Digitizers generally include a manually movable cursor and tablet having a planar sensing surface. A sheet bearing a two-dimensional design such as a graphic illustration, technical drawing, etc., is placed on the sensing surface of the tablet and an operator manually moves the cursor on the surface of the sheet to trace selected features of the design. Cross-hairs in a position-sighting aperture of the cursor may be used to align the cursor with a desired feature of the design.
The operator, by pressing a button on the cursor, may direct a computer connected to the digitizer to perform a particular operation based on the coordinates relative to the tablet of a particular point on the sheet below the cross-hairs. The coordinates of that particular point may then be used by the computer in accordance with a software program, e.g., a computer-aided design program (CAD). The position coordinates of the desired feature are determined by an interaction between, for example, inductive or capacitive elements in the digitizing tablet and the cursor.
Operator error in determining the proper position for the cursor is frequently a significant limitation on digitizer accuracy rather than the resolution or the accuracy provided by the digitizer. Magnification of the details of the design may assist the operator in correctly positioning the cursor. However, a magnifying lens carried by a cursor to provide such desired magnification may interfere with use of the cursor when such magnification is not needed. For example, the magnifying lens restricts the operator's field of view in the area of the position-sighting aperture, and may interfere with the operator's ability to quickly recognize and locate desired details. Thus, while it may be desirable to magnify a surface below the cross-hairs to precisely position the cursor, it may also be desirable at other times to provide a clear line of sight for the operator to the position-sensing aperture.
A magnifier and holder for the magnifier which removably attaches to a cursor is currently available from Summagraphics Corporation, the assignee of this application. Co-pending U.S. patent application Ser. No. 199,674, filed May 27, 1988, of Murray, assigned to the assignee of this application, now U.S. Pat. No. 5,014,044 discloses a cursor having a magnifier which may be moved out of the position-sighting aperture line of sight, and which may be removed from the cursor. While in the application referred to above and in the device referred to above the magnifier may be moved out of the line of sight of the position-sighting aperture, and in the device referred to above the holder may be removed from the cursor, there is room for improvement, functionally, operationally, and/or aesthetically, in achieving magnification while providing for moving the magnifier out position-sighting aperture line of sight and removing the magnifier.